1. Field of the Invention
This invention relates to mechanisms for the handling and application of materials, and more particularly to a mechanism for the preparation, handling, and application of liquified materials such as coating compounds, joint sealers, crack fillers, waterproofing compounds and other materials commonly used in the construction arts.
2. Description of the Prior Art
For many years, especially designed machines have been used for preparing, handling and applying the various liquified compounds used by the construction industry for filling, sealing, coating and related purposes. A specific type of such machine, hereinafter referred to as an asphalt machine, is employed for the preparation, handling and application of an asphalt-rubber composition used for jobs such as surfacing paved surfaces, filling and sealing cracks and joints in roadways, runways and other paved surfaces, repairing and coating roofing, and the like.
These so-called asphalt machines all include the same basic components of a materials tank which is provided with a suitable heating means to change the asphalt-rubber composition from its normally solid state to its molten state and maintain that molten state. An externally driven mixing mechanism is mounted in the materials tank to mix and maintain the granulated rubber and hot asphalt in a homogeneous state, and a pump is coupled to the outlet of the materials tank to deliver the molten asphalt-rubber composition to a suitable application device.
Several problems exist in the prior art asphalt machines partly due to the inherent characteristics of the asphalt-rubber composition itself, and partly due to the design of these prior art machines. It is well known that molten asphalt-rubber is a relatively heavy or thick, messy liquid which contaminates everything it comes in contact with. Thus, machines for handling and applying this material must be heavy duty, must be capable of maintaining the molten state of the material, and must be provided with a cleanout system.
With regard to the drive means provided on the prior art asphalt machines for pumping and mixing the molten asphalt-rubber composition, traditionally, the drive means includes an engine which is mechanically coupled to the mixer and pump by means such as a chain drive, clutch devices and/or the like. Such mechanical coupling results in frequent engine stalling particularly when the mixing mechanism is subjected to inconsistent loads when the asphalt-rubber composition is being melted, and also when the flow of the molten material being pumped is interrupted by the operator shutting down the applicator device and causing a sudden increase in line pressure and resultant loading of the materials pump. The frequent engine stalling is not only time consuming and inconvenient to the machine's operator, but it also subjects the machine's components to stresses which shorten the life of the machine.
The heating means provided on the prior art asphalt machines usually take the form of propane heaters which are continuously operated when materials are in the tank to prevent solidification thereof. No provisions are made for standby heating devices which would utilize an alternate more readily available energy form, and would reduce energy consumption during periods when the machine is not being used such as overnight, or when material application is delayed for other reasons. Thus, when such delays occur the heaters of the prior art asphalt machines must either be continuously operated, or otherwise considerable time must be expended to re-melt the asphalt-rubber compound.
Due to the relatively rapid solidification of the molten asphalt-rubber composition, means must be provided on the handling and application machines for pre-heating the applicator hoses and heating of the other lines through which the molten materials flow. Some of the prior art asphalt machines provide pre-heating storage compartments for the applicator hoses, however, to the best of our knowledge, none heat the materials flow line between the materials pump and the applicator hose and reduce the severity of solidification by keeping such lines as short as possible.
With regard to cleanout systems for purging of the materials pump and materials flow lines and hoses, the prior art machines usually carry tanks of solvent which is pumped through the various components to remove materials therefrom. Some of the prior art asphalt machines accomplish this cleanout function better than others, however, none to our knowledge, provide reversible flow of the solvent within the components.
Therefore, a new and improved materials handling and application mechanism is needed to overcome some of the problems and shortcomings of the prior art.